This invention relates to liquid crystal displays and more particularly to methods and systems for controlling the voltages driving liquid crystal displays.
Present-day electronic systems, such as calculators, timepieces, and the like, having multiplexed liquid crystal displays, require a regulated voltage Vp and fractional voltages for driving the segments and backplanes of the liquid crystal display. In prior art multiplexed liquid crystal display systems, voltage driving the display is controlled by means of a device such as a voltage regulator to match the driving voltage with the particular material used in the display. A center tap, for example, between a series of diodes and resistors provides the fractional voltage needed to drive the display. Controlling voltage by means of a regulator and center tap is difficult and results in unwanted consumption of power.
It is therefore an object of the present invention to provide an improved system and method of controlling liquid crystal display drive voltages.
It is another object of the present invention to provide means for lowering the root mean square voltage driving a liquid crystal display to match the particular display material without using a voltage regulator.
It is yet another object of the present invention to provide an improved means for varying the root mean square voltage driving a liquid crystal display with reduced power consumption.
It is a further object of the present invention to provide a means for controlling the root means square voltage driving a liquid crystal display that is suitable for use with a silver oxide battery and doubler system with low power CMOS circuitry.